It is known to mount a fuel pressure regulator on a fuel rail assembly to regulate the pressure of the fuel that is supplied to the fuel injectors mounted on the fuel rail. The pressurized fuel that is delivered to the fuel rail is pumped from a fuel tank through a fuel supply conduit and excess fuel is returned from the fuel pressure regulator's return port through a fuel return conduit to the tank. This type of system is called a return type system. A typical fuel pressure regulator used in this system provides a movable wall or diaphragm dividing the regulator into chambers on opposite sides thereof at different pressures. The difference in pressure determines the position of the diaphragm, which in turn determines the size of a flow passage through the regulator. Thus, depending upon the difference in pressure on opposite sides of the diaphragm, the flow through the regulator is regulated to a predetermined pressure.
Another type of fuel injection system does not have a fuel return conduit and is called a returnless (non-return or dead head) fuel system. In this system, the diaphragm controls the position of a ball valve which is spring-based toward a valve-seat. Fuel flows past the spring and normally opened ball valve into a compartment on one side of the diaphragm for flow to a fuel rail. The opposite side of the diaphragm may have a vacuum reference. It will be appreciated that the difference in pressure between the chambers on the opposite sides of the diaphragm displaces the diaphragm, which in turn mounts a post for moving the ball valve away from the seat or permitting the ball valve to move toward the seat under the spring bias.
Such systems are satisfactory for use in providing fuel to a fuel rail at a predetermined regulated pressure. While such pressure regulators have proven satisfactory, there is a need to maximize performance of the combustion engine to which fuel is supplied from the fuel pressure regulator. A combustion engine should not be supplied fuel that is turbulent or aerated. To avoid turbulent flow and aerated fuel, it is generally desirable to maintain a constant level of fuel within and about the fuel pressure regulator. This requires submersing the fuel pressure regulator in fuel. An added benefit from this is the potential reduction in noise. There has developed a need in the mechanical fuel system for a fuel pressure regulator which provides the desired engine performance for a simple and inexpensive means to keep a fuel pressure regulator submersed in fuel.